JP4673870B2 - Fuel injection device for backbone type motorcycle - Google Patents

Description

  According to the present invention, a vehicle body frame is constituted by a backbone extending obliquely rearward and downward from a head pipe that supports a front fork, and a rear frame that is integrally coupled to the rear end of the backbone and supports a rear fork. An engine that causes a cylinder block and a cylinder head to project substantially horizontally forward from below the backbone is attached to the frame, an intake port that opens to the top surface of the cylinder head, and an air cleaner that is disposed at the front end of the backbone; The present invention relates to a fuel injection device for a backbone type motorcycle in which a throttle valve is provided at an intermediate portion of the intake passage, which is disposed below the backbone via an intake passage which is inclined downwardly and rearwardly.

Such a backbone type motorcycle is widely used worldwide as a small motorcycle with the trade name “Super Cub” related to the manufacture of the applicant company. In this case, a vaporizer is installed in the middle of the intake passage. (For example, refer to Patent Document 1 below).
Japanese Utility Model Publication No. 62-39993

  In the backbone type motorcycle described above, if the fuel injection valve is attached to the intake passage instead of the carburetor without changing the body frame or the engine layout, the injected fuel is supplied from the fuel injection valve to the cylinder head of the engine. In order to be surely directed to the intake port that opens on the upper surface of the intake passage, it must be attached to the upper side wall of the intake passage. However, since the backbone of the frame is disposed relatively close above the intake passage, the fuel injection valve easily interferes with the backbone and cannot be easily attached to the upper side wall of the intake passage. .

  Therefore, the present invention can attach the fuel injection valve to the upper side wall of the intake passage without interfering with the backbone of the body frame without changing the layout of the conventional body frame and engine. It is an object of the present invention to provide a fuel injection device for the backbone type motorcycle that can inject fuel toward an intake port of a cylinder head.

  In order to achieve the above object, the present invention includes a backbone extending obliquely rearward and downward from a head pipe that supports a front fork, and a rear frame that is integrally coupled to the rear end of the backbone and supports a rear fork. A vehicle body frame is configured, and an engine for projecting the cylinder block and the cylinder head substantially horizontally toward the front below the backbone is attached to the rear frame, an intake port opening on the upper surface of the cylinder head, and the backbone The air cleaner disposed at the front end is connected via an intake passage which is disposed below the backbone and is inclined substantially rearward and downward, and a throttle valve is provided at an intermediate portion of the intake passage. Legs covering block, cylinder head, air cleaner and intake passage In a backbone type motorcycle in which a shield is attached to the vehicle body frame, the intake passage is obtuse forward along the backbone while rising from the upper surface of the cylinder head so as to secure a space between the intake passage and the backbone. Along the backbone to connect between the first and second bent portions, a first bent portion bent at a lower surface of the air cleaner, a second bent portion bent backward along the backbone at an obtuse angle, and the first and second bent portions. A fuel injection valve is erected on the upper side wall of the first bent portion facing the intake port, and the fuel is directed downward from the valve toward the intake port of the cylinder head. The fuel injection valve disposed immediately below the backbone and the fuel injection valve are disposed in the space. A fuel supply pipe connected to the end and extending in a direction intersecting with the axial direction of the fuel injection valve and disposed close to the lower surface of the backbone; and the throttle valve is disposed in the linear portion. This is the first feature.

According to the present invention, in addition to the first feature, the first bent portion is constituted by an intake pipe coupled to the upper surface of the cylinder head, and the straight portion is connected to an upstream end of the intake pipe. The throttle valve is configured as an intake passage, and the throttle valve is configured as a butterfly valve type that opens and closes the intake passage, and the rotation axis of the throttle valve is disposed in a horizontal direction perpendicular to the backbone, and the throttle valve The second feature is that it is supported by the body.

  Further, according to the present invention, in addition to the second feature, the intake pipe starts to bend along the backbone from a joint surface with the upper surface of the cylinder head, and the joint surface of the intake pipe with the cylinder head A third feature is that the joint surface of the intake pipe and the downstream end of the throttle body form an obtuse angle.

  According to the first feature of the present invention, it is possible to attach to the upper side wall of the intake passage by rationally using the small space between the backbone and the intake passage without changing the layout of the conventional body frame and engine. While the fuel injection valve is housed together with the fuel supply pipe, fuel can be injected downward from the fuel injection valve toward the intake port of the cylinder head. In addition, the intake passage connecting the air cleaner and the intake port includes a first bent portion that bends forward at an obtuse angle along the backbone while rising from the upper surface of the cylinder head so as to secure a space between the intake passage and the backbone, and an air cleaner. The intake passage is composed of a second bent portion that bends backward at an obtuse angle along the backbone while descending from the lower surface of the pipe, and a straight portion that extends along the backbone to connect the first and second bent portions. Since it is inclined backward and downward as a whole while securing the space with the backbone, the intake resistance is reduced, which can contribute to the improvement of the output of the engine E.

  According to the second feature of the present invention, on the downstream side of the throttle valve, fuel can be injected from the fuel injection valve through the intake pipe toward the intake port of the cylinder head, particularly toward the downstream end where the intake valve is located. Therefore, loss due to fuel adhering to the pipe wall can be reduced.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 4 show a first embodiment of the present invention. FIG. 1 is a side view of a backbone type motorcycle, FIG. 2 is a side view around an engine and an intake system of the motorcycle, and FIG. FIG. 4 is an enlarged side view of the vicinity of the fuel injection device in the intake system of FIG. 4, FIG. 4 is a view taken in the direction of arrow 4 in FIG. 3, and FIG. 5 is a side view similar to FIG.

  First, a first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a vehicle body frame F of a motorcycle M is welded to the rear side surface of the head pipe 1 at the front end, and is welded to a backbone Ff made of a steel pipe extending obliquely rearward and downward, and to the rear end of the backbone Ff. A rear frame Fr made of a steel plate is configured. A front fork 2 that pivotally supports the front wheel Wf is pivotally supported on the head pipe 1 and a rear fork 3 that pivotally supports the rear wheel Wr is pivotally supported on the rear frame Fr. The rear cushion 4 is connected between the rear frames Fr. A saddle 5 is attached to the upper surface of the rear frame Fr, and the fuel tank 6 is housed and held in the rear frame Fr immediately below the saddle 5. Furthermore, the crankcase 7 of the engine E is attached to the front end of the rear frame Fr below the connection point with the backbone Ff. The engine E has a cylinder block 8 that protrudes from the front surface of the crankcase 7 and is disposed substantially horizontally. An air cleaner 10 is attached to the front end portion of the backbone Ff, and this is connected to an intake port (see FIG. 2) of the cylinder head 9 via an intake passage 12 disposed below the backbone Ff.

  The backbone Ff, the cylinder block 8, the cylinder head 9, the air cleaner 10, and the intake passage 12 are covered with a leg shield 13 attached to the vehicle body frame F.

  As shown in FIGS. 2 and 3, the backbone Ff is coupled to the head pipe 1 and has a front half straight line portion 14a inclined downward and downwardly extending linearly, and a lower slope with a lower inclination than the front half straight line portion 14a. The second straight line portion 14b that extends linearly and is coupled to the rear frame Fr, and the intermediate bent portion 14c having a radius of curvature R that continuously couples the two straight line portions 14a and 14b. The cylinder head 9 is located below the intermediate bent portion 14c, and the intake port 11 is opened on the upper surface of the cylinder head 9. An opening end of the intake port 11 to the combustion chamber 16 is opened and closed by an intake valve 15.

  The air cleaner 10 includes a cleaner case 17 that is disposed immediately below the front straight line portion 14a of the backbone Ff and has a front surface opened, a case cover 18 that is coupled to the cleaner case 17 and closes the open surface, and the cleaner case 17 and The cleaner element 19 is sandwiched between the case covers 18 and an inlet duct 20 connected to the upper end of the case cover 18. A connection hole 21 for the intake passage 12 is provided in the bottom wall of the cleaner case 17. Then, the inlet duct 20 and the cleaner case 17 are screwed to the front half straight portion 14a of the backbone Ff.

  The above is no different from the layout of a conventional small motorcycle.

  The intake passage 12 includes a horn pipe 22 that is fitted into the connection hole 21 and enters the cleaner case 17, an intake pipe 23 that is coupled to the upper surface of the cylinder head 9 to communicate with the intake port 11, and A throttle body 24 is connected between the horn pipe 22 and the intake pipe 23. The horn tube 22 has an obtuse bent portion in the middle and has a substantially L shape with the downstream opening end facing backward and downward. The intake pipe 23 also has an obtuse bent portion in the middle and has an upstream opening end. It has a substantially L shape with the front facing upward. That is, the intake pipe 23 rises from the upper surface of the cylinder head 9 and bends forward at an obtuse angle along the backbone Ff. In particular, the bend starts from the joint surface with the cylinder head 9. A space S is secured between the bent intake pipe 23 and the backbone Ff. The throttle body 24 arranged to be inclined so as to connect the pipes 22 and 23 has a straight intake passage 24a communicating with the inside of the pipes 22 and 23, and is a butterfly type that opens and closes the intake passage 24a. The throttle valve 25 is pivotally supported by the throttle body 24 with its rotating shaft 25a oriented in a horizontal direction perpendicular to the backbone Ff. The intake pipe 23 is formed such that the joint surface with the upper surface of the cylinder head 9 and the joint surface with the downstream end of the throttle body 24 form an obtuse angle. In this way, the intake passage 12 is disposed substantially along the backbone Ff.

  An electromagnetic fuel injection valve 30 is erected on the bent portion of the substantially L-shaped intake pipe 23 or on the upper side wall in the vicinity thereof. That is, a boss 27 having a mounting hole 26 is integrally formed on the bent portion of the intake pipe 23 or the upper side wall in the vicinity thereof, and the lower end portion of the fuel injection valve 30 is inserted into the valve mounting hole 26 via the seal member 28. It is fitted. A fuel inlet is opened at the upper end surface of the fuel injection valve 30 and a fuel injection hole is opened at the lower end surface. The fuel injection valve 30 is directed to a downstream end of the intake port 11 where the injected fuel 31 is opened and closed by the intake valve 15, and the upper end of the fuel injection valve 30 is an outer curve at the intermediate bent portion 14 c of the backbone Ff. It arrange | positions so that it may come ahead from the midpoint 32. FIG.

  As shown in FIGS. 3 and 4, a mounting hole 35 that opens to the side wall of the fuel supply pipe 34 is fitted to the upper end portion of the fuel injection valve 30 via a seal member 36. The fuel supply pipe 34 is disposed directly below the backbone Ff and perpendicular to the axis Y of the backbone Ff, that is, in the left-right direction of the vehicle body. A fuel conduit 39 connected to a discharge port of a fuel pump 38 (see FIG. 1) disposed in the fuel tank 6 is connected to one end of the fuel supply pipe 34, and an injection pressure regulator 40 is connected to the other end. Are concatenated. Thus, the fuel injection valve 30 erected on the upper side wall of the intake pipe 23 is accommodated in the space S while the fuel supply pipe 34 connected to the upper end thereof is brought close to the backbone Ff.

  As shown in FIG. 4, the injection pressure regulator 40 includes a regulator body 42 having a fuel chamber 41 communicating with the fuel supply pipe 34, and a cap 44 having a boost negative pressure chamber 43 and coupled to the regulator body 42. And a diaphragm 45 that is sandwiched between the regulator body 42 and the cap 44 and partitions the fuel chamber 41 and the boost negative pressure chamber 43. A valve seat 47 in which a fuel return hole 46 is opened is provided at the center of the regulator body 42, and a valve body 48 that can be seated on the valve seat 47 is attached to the center of the diaphragm 45 so as to swing. A valve spring 49 that urges the valve body 48 toward the valve seat 47 through the diaphragm 45 is accommodated in the boost negative pressure chamber 43. The boost negative pressure chamber 43 communicates with the intake pipe 23 via a negative pressure conduit 50, and the fuel return hole 46 communicates with the fuel tank 6 via a fuel return pipe 51. Further, a fuel filter 52 is provided in the fuel chamber 41.

  Next, the operation of the first embodiment will be described.

  During operation of the engine E, the fuel in the fuel tank 6 is pumped into the fuel chamber 41 of the injection pressure regulator 40 through the fuel conduit 39 and the fuel supply pipe 34 by the fuel pump 38, and the fuel pressure causes the valve body 48 to be seated. Acts on the diaphragm 45 in a direction away from the diaphragm 47. On the other hand, the boost negative pressure in the intake pipe 23 is introduced into the boost negative pressure chamber 43 through the negative pressure conduit 50, and this boost negative pressure causes the valve body 48 to act as a valve seat, contrary to the load direction of the valve spring 49. Acts on the diaphragm 45 in a direction away from the diaphragm 47. Therefore, when the load on the engine E is small and the boost negative pressure is high, the valve opening pressure of the valve body 48 by the fuel in the fuel chamber 41 is low, and when the load on the engine E is large and the boost negative pressure is low, the fuel chamber The valve opening pressure of the valve body 48 due to the fuel 41 becomes high, and when the valve body 48 is opened, it returns to the fuel tank 6 through the fuel return pipe 51 that has flowed out of the fuel chamber 41 into the fuel return hole 46. Thus, the fuel pressure in the fuel supply pipe 34 is controlled according to the load of the engine E.

  Thus, during the intake stroke of the engine E, when the intake valve 15 is opened and the fuel injection valve 30 is excited and opened, the pressure-controlled fuel is injected from the valve 30 as described above. Since 31 is directed to the downstream end of the intake port 11 opened by the intake valve 15, the intake port 11 is efficiently sucked into the fuel chamber 41 together with the intake air filtered by the air cleaner 10 and flowing down the intake passage 12. Therefore, there is little loss due to adhesion of the injected fuel 31 to the pipe wall, which can contribute to reduction of fuel consumption. In addition, the intake passage 12 connecting the air cleaner 10 and the intake port 11 is only inclined by the horn pipe 22 and the intake pipe 23 at an obtuse angle, and as a whole is inclined backward and downward, the intake resistance is reduced, and the engine E Can contribute to the improvement of the output.

  By the way, the fuel injection valve 30 is erected on the bent portion of the intake pipe 23 or the upper side wall in the vicinity thereof, and at least the upper end of the valve 30 comes forward from the midpoint 32 of the outer curve in the intermediate bent portion 14c of the backbone Ff. Therefore, without changing the layout of the conventional vehicle body frame F or engine E, the narrow space S between the backbone Ff and the intake passage 12 can be used rationally, and the upper wall of the intake passage 12 can be used. Therefore, it is possible to inject fuel from the valve 30 toward the downstream end of the intake port 11 as described above.

  In addition, the fuel supply pipe 34 connected to the upper end of the fuel injection valve 30 is disposed horizontally and perpendicular to the axis of the backbone Ff, so that the fuel supply pipe 34 is disposed in a narrow space between the backbone Ff and the fuel injection valve 30. It can be easily arranged without being interfered by the backbone Ff.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the fuel supply pipe 34 connected to the upper end of the fuel injection valve 30 is disposed in a rearward downward inclination along the lower surface of the backbone Ff, and the backbone Ff is connected to the rear end of the fuel supply pipe 34. The configuration is the same as that of the previous embodiment except that the fuel conduit 39 arranged along the line and the regulator body 42 of the injection pressure regulator 40 are integrally connected to the front end of the fuel supply pipe 34. In the figure, parts corresponding to those of the previous embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Thus, since the fuel supply pipe 34 is disposed rearwardly and downwardly along the lower side surface of the backbone Ff, the fuel supply pipe 34 is placed in a narrow space between the backbone Ff and the fuel injection valve 30 in this case as well. Can be easily arranged without being interfered by. Further, since the fuel conduit 39 connected to the rear end of the fuel supply pipe 34 is disposed along the backbone Ff, the fuel conduit 39 does not protrude greatly from the backbone Ff, and it is easy to interfere with other objects. It can be avoided.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention.

1 is a side view of a backbone type motorcycle showing a first embodiment of the present invention. Fig. 2 is a side view around the engine and the intake system of the motorcycle. FIG. 3 is an enlarged side view around a fuel injection device in the intake system of FIG. 2. FIG. 4 is a view taken in the direction of arrow 4 in FIG. 3. The side view similar to FIG. 3 which shows 2nd Example of this invention.

E ... Engine F ... Body frame Ff ... Backbone Fr ... Rear frame S ... Space Y ... Backbone axis 1 ... Head pipe 2 ... Front fork 3 ... Rear fork 8 ... Cylinder block 9 ... Cylinder head 10 ... Air cleaner 11 ... Air intake port 12 ... .... Intake passage 23 ... Intake pipe 24 ... Throttle body 24a ... Intake passage 25 ... Throttle valve 30 ... Fuel injection valve 34 ... Fuel supply pipe

Claims (3)

A backbone (Ff) extending obliquely rearward and downward from the head pipe (1) supporting the front fork (2), and a rear supporting the rear fork (3) by integrally connecting to the rear end of the backbone (Ff) The frame (Fr) constitutes a vehicle body frame (F), and the cylinder block (8) and the cylinder head (9) are placed substantially horizontally toward the rear frame (Fr) below the backbone (Ff). A projecting engine (E) is attached, and the backbone between the intake port (11) opening on the upper surface of the cylinder head (9) and the air cleaner (10) disposed at the front end of the backbone (Ff) is provided. (Ff) is connected via an intake passage (12) which is disposed below (Ff) and is inclined rearward and downward, and a slot is formed in the middle portion of the intake passage (12). A leg shield (13) provided with a valve (25) and covering the backbone (Ff), cylinder block (8), cylinder head (9), air cleaner (10) and intake passage (12) is provided on the vehicle body frame (F). In the installed backbone type motorcycle,
The intake passage (12) rises along the backbone (Ff) while rising from the upper surface of the cylinder head (9) to secure a space (S) between the intake passage (12) and the backbone (Ff). A first bent portion (23) bent forward at an obtuse angle, a second bent portion (22) bent downward at an obtuse angle along the backbone (Ff) while descending from the lower surface of the air cleaner (10), The first and second bent portions ( 23, 22 ) are connected to the intake port of the first bent portion (23) by extending along the backbone (Ff) to connect the first and second bent portions ( 23, 22 ). A fuel injection valve (30) is erected on the upper side wall facing (11), and fuel is injected downward from the valve (30) toward the intake port (11) of the cylinder head (9). , The space (S) is connected to the fuel injection valve (30) disposed immediately below the backbone (Ff) and the upper end of the fuel injection valve (30). A fuel supply pipe (34) extending in a direction intersecting the axial direction and disposed in the vicinity of the lower surface of the backbone (Ff) is accommodated, and the throttle valve (25) is disposed in the straight portion (24a). A fuel injection device for a backbone type motorcycle. The fuel injection device for a backbone type motorcycle according to claim 1,
The first bent portion is constituted by an intake pipe (23) coupled to the upper surface of the cylinder head (9), and the straight portion is connected to an upstream end of the intake pipe (23). ), And the throttle valve (25) is configured as a butterfly valve that opens and closes the intake passage (24a), and the rotation shaft (25a) of the throttle valve (25). Is disposed in a horizontal direction perpendicular to the backbone (Ff) and is supported by the throttle body (24). A fuel injection device for a backbone type motorcycle. The fuel injection device for the backbone type motorcycle according to claim 2,
The intake pipe (23) starts to bend along the backbone (Ff) from the joint surface with the upper surface of the cylinder head (9), and the intake pipe (23) is connected to the cylinder head (9). A fuel injection device for a backbone type motorcycle, characterized in that a joint surface and a joint surface between the intake pipe (23) and the downstream end of the throttle body (24) form an obtuse angle.

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